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nptl: Change type of __default_pthread_attr

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union pthread_attr_transparent has always the correct size, even if
pthread_attr_t has padding that is not present in struct pthread_attr.

This should not result in an observable behavioral change.  The
existing code appears to have been correct, but it was brittle because
it was not clear which functions were allowed to write to an entire
pthread_attr_t argument (e.g., by copying it).

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer
2020-05-18 18:25:18 +02:00
parent 86ed0774cf
commit c2322a561f
8 changed files with 14 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
nptl/allocatestack.c
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@ -425,7 +425,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
else else
{ {
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
size = __default_pthread_attr.stacksize; size = __default_pthread_attr.internal.stacksize;
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
} }

4
nptl/nptl-init.c
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@ -318,8 +318,8 @@ __pthread_initialize_minimal_internal (void)
/* Round the resource limit up to page size. */ /* Round the resource limit up to page size. */
limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz); limit.rlim_cur = ALIGN_UP (limit.rlim_cur, pagesz);
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
__default_pthread_attr.stacksize = limit.rlim_cur; __default_pthread_attr.internal.stacksize = limit.rlim_cur;
__default_pthread_attr.guardsize = GLRO (dl_pagesize); __default_pthread_attr.internal.guardsize = GLRO (dl_pagesize);
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
#ifdef SHARED #ifdef SHARED

2
nptl/pthreadP.h
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@ -199,7 +199,7 @@ enum
/* Default pthread attributes. */ /* Default pthread attributes. */
extern struct pthread_attr __default_pthread_attr attribute_hidden; extern union pthread_attr_transparent __default_pthread_attr attribute_hidden;
extern int __default_pthread_attr_lock attribute_hidden; extern int __default_pthread_attr_lock attribute_hidden;
/* Size and alignment of static TLS block. */ /* Size and alignment of static TLS block. */

2
nptl/pthread_attr_getstacksize.c
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@ -33,7 +33,7 @@ __pthread_attr_getstacksize (const pthread_attr_t *attr, size_t *stacksize)
if (size == 0) if (size == 0)
{ {
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
size = __default_pthread_attr.stacksize; size = __default_pthread_attr.internal.stacksize;
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
} }
*stacksize = size; *stacksize = size;

8
nptl/pthread_create.c
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@ -612,16 +612,16 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
STACK_VARIABLES; STACK_VARIABLES;
const struct pthread_attr *iattr = (struct pthread_attr *) attr; const struct pthread_attr *iattr = (struct pthread_attr *) attr;
struct pthread_attr default_attr; union pthread_attr_transparent default_attr;
bool destroy_default_attr = false; bool destroy_default_attr = false;
bool c11 = (attr == ATTR_C11_THREAD); bool c11 = (attr == ATTR_C11_THREAD);
if (iattr == NULL || c11) if (iattr == NULL || c11)
{ {
int ret = __pthread_getattr_default_np ((pthread_attr_t *) &default_attr); int ret = __pthread_getattr_default_np (&default_attr.external);
if (ret != 0) if (ret != 0)
return ret; return ret;
destroy_default_attr = true; destroy_default_attr = true;
iattr = &default_attr; iattr = &default_attr.internal;
} }
struct pthread *pd = NULL; struct pthread *pd = NULL;
@ -852,7 +852,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
out: out:
if (destroy_default_attr) if (destroy_default_attr)
__pthread_attr_destroy ((pthread_attr_t *) &default_attr); __pthread_attr_destroy (&default_attr.external);
return retval; return retval;
} }

3
nptl/pthread_getattr_default_np.c
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@ -22,8 +22,7 @@ int
__pthread_getattr_default_np (pthread_attr_t *out) __pthread_getattr_default_np (pthread_attr_t *out)
{ {
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
int ret = __pthread_attr_copy (out, int ret = __pthread_attr_copy (out, &__default_pthread_attr.external);
(pthread_attr_t *) &__default_pthread_attr);
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
return ret; return ret;
} }

6
nptl/pthread_setattr_default_np.c
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@ -68,15 +68,15 @@ pthread_setattr_default_np (const pthread_attr_t *in)
/* Preserve the previous stack size (see above). */ /* Preserve the previous stack size (see above). */
if (temp.internal.stacksize == 0) if (temp.internal.stacksize == 0)
temp.internal.stacksize = __default_pthread_attr.stacksize; temp.internal.stacksize = __default_pthread_attr.internal.stacksize;
/* Destroy the old attribute structure because it will be /* Destroy the old attribute structure because it will be
overwritten. */ overwritten. */
__pthread_attr_destroy ((pthread_attr_t *) &__default_pthread_attr); __pthread_attr_destroy (&__default_pthread_attr.external);
/* __default_pthread_attr takes ownership, so do not free /* __default_pthread_attr takes ownership, so do not free
attrs.internal after this point. */ attrs.internal after this point. */
__default_pthread_attr = temp.internal; __default_pthread_attr = temp;
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
return ret; return ret;

2
nptl/vars.c
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@ -22,7 +22,7 @@
/* Default thread attributes for the case when the user does not /* Default thread attributes for the case when the user does not
provide any. */ provide any. */
struct pthread_attr __default_pthread_attr attribute_hidden; union pthread_attr_transparent __default_pthread_attr attribute_hidden;
/* Mutex protecting __default_pthread_attr. */ /* Mutex protecting __default_pthread_attr. */
int __default_pthread_attr_lock = LLL_LOCK_INITIALIZER; int __default_pthread_attr_lock = LLL_LOCK_INITIALIZER;